The lubrication of equipment, such as knitting machinery, is often accomplished by the use of an oil mist lubrication system. In such systems, lubricating oil is suspended as an aerosol or mist in a stream of air, and is carried through a tube to a remote location requiring lubrication. The oil is placed in the aerosol state at a central mist-generating location and then may be transmitted by a distributor to the desired locations at the equipment.
Improvements in the efficiency of mist transmission, as well as the development of distribution spray nozzles which are capable of delivering precisely-directed mists at low flow rates, necessitate mist generators which are capable of generating and delivering oil mist streams which are of the appropriate oil concentration. Due to the construction of many conventional generators, this requirement has been difficult to meet.
In particular, generators of the type as shown in U.S. Pat. No. 4,353,435, utilize a mist generator which includes a chamber into which an oil mist is sprayed. The oil mist exits the chamber through a series of fittings or barbs extending through the upper end of the chamber, the barbs having tubes affixed thereto to deliver the mist as required. Because of the positioning of the barbs, however, it has been found that the oil spray, containing both the airborne oil mist and heavy droplets which the upper, inner surface of the chamber and the exposed exterior surfaces of the barbs comes out of suspension and forms a solid oil film which migrates to the lower end of the barbs under the influence of gravity. The film collects at the end of the barb, and is captured by the oil spray stream entering the barbs into and through the barbs and tubes, in addition to the mist being carried thereby, whereby the amount of oil ultimately dispensed by the lubrication system is greater than that intended for distribution by the mist alone.
A decrease in the volume of oil being transmitted can be accomplished by a reduction in the volumetric air flow rate through the chamber, such as by decreasing the pressure thereof. With decreased pressure, however, insufficient velocity is provided to the mist whereby the flow and dispersion characteristics of the lubrication system can be distorted and degraded. In addition, a certain velocity level is needed to create a proper mist.
Accordingly, it is a purpose of the present invention to provide an improved oil mist generator which is capable of improved control over low oil volume flow rates.
Another purpose of the present invention is to provide an improved oil mist generator having means for collecting and recycling oil which collects on interior portions of the generator.
Yet another purpose of the present invention is to provide an improved oil mist generator having resistance to overload resulting from unwanted mist collection.
A further purpose of the present invention is to provide such an improved oil mist generator which is of economical construction and which requires minimal alteration to conventional systems.
Still another purpose of the present invention is to allow two levels of lubrication to be provided from a simple mist generator unit.